scholarly journals INVESTIGATION OF POSSIBILITY OF THE MISFIT DISLOCATION DENSITY REDUCTION IN GE / SI FILMS WITH A BUFFER LAYER

2021 ◽  
pp. 263-271
Author(s):  
Вячеслав Анатольевич Лапин ◽  
Александр Александрович Кравцов ◽  
Дмитрий Сергеевич Кулешов ◽  
Федор Федорович Малявин
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Three Dimensional ◽  
Growth Time ◽  
Misfit Dislocations ◽  
Technological Parameters ◽  
Island Growth ◽  
Density Reduction ◽  
Si Films

В работе исследована возможность улучшения качества гетероэпитаксиальных структур Ge / Si с буферным слоем. Показано, что при использовании подготовительного слоя, состоящего из наноостровков, зарощенных низкотемпературным буферным слоем, возможно проявление так называемого эффекта аннигиляции дислокаций несоответствия в объеме буферного слоя Buf, что значительно улучшает приборное качество получаемых структур. Представлена зависимость морфологии поверхности слоя чистого Ge на буфере от времени роста наноостровков в интерфейсе Si / Buf . Выявлены оптимальные технологические параметры роста наноостровков для получения слоя Ge с минимальной значением шероховатости. Наилучших результатов удалось достичь при времени осаждения наноостровков 2 мин. При этом была достигнута минимальное значение шероховатости поверхности, равное 78 нм. Показано, что при дальнейшем увеличении размеров наноостровков, процесс аннигиляции дефектов замедляется, и рост низкотемпературного буферного слоя сменяется трехмерным островковым ростом, что увеличивает перепады рельефа поверхности выращиваемого слоя. The possibility of improving the quality of Ge / Si heteroepitaxial structures with a buffer layer is investigated. It is shown that when using a preparatory layer consisting of nanostructures overgrown with a low-temperature buffer layer, it is possible to manifest the so-called effect of annihilation of the misfit dislocations in the bulk of the buffer layer Buf , which significantly improves the quality of the resulting structures. The dependence of the morphology of the surface of the pure Ge layer on the buffer on the growth time of nanostructures in the Si / Buf interface is presented. The optimal technological parameters of the growth of nanostructures for obtaining a Ge layer with a minimum roughness value are revealed. The best results were achieved when the deposition time of nanostructures was 2 min. At the same time, the minimum surface roughness value of 78 nm was achieved. It is shown that with a further increase in the size of the nanostructures, the process of annihilation of defects slows down, and the growth of the low-temperature buffer layer is replaced by a three-dimensional island growth, which increases the differences in the relief of the surface of the grown layer.

Experimental study on the accuracy and surface quality of printed versus machined holes in PEI Ultem 9085 FDM specimens

2021 ◽  
Vol 27 (11) ◽  
pp. 1-12
Author(s):  
Giovanni Gómez-Gras ◽  
Marco A. Pérez ◽  
Jorge Fábregas-Moreno ◽  
Guillermo Reyes-Pozo
Keyword(s):  
Surface Quality ◽  
Fused Deposition Modeling ◽  
Three Dimensional ◽  
Dimensional Accuracy ◽  
Technological Parameters ◽  
Content Type ◽  
Fused Deposition ◽  
Comparison Of The Results ◽  
Through Hole

Purpose This paper aims to investigate the quality of printed surfaces and manufacturing tolerances by comparing the cylindrical cavities machined in parts obtained by fused deposition modeling (FDM) with the holes manufactured during the printing process itself. The comparison focuses on the results of roughness and tolerances, intending to obtain practical references when making assemblies. Design/methodology/approach The experimental approach focuses on the comparison of the results of roughness and tolerances of two manufacturing strategies: geometric volumes with a through-hole and the through-hole machined in volumes that were initially printed without the hole. Throughout the study, both alternates are explained to make appropriate recommendations. Findings The study shows the best combinations of technological parameters, both machining and three-dimensional printing, which have been decisive for obtaining successful results. These conclusive results allow enunciating recommendations for use in the industrial environment. Originality/value This paper fulfills an identified need to study the dimensional accuracy of the geometries obtained by additive manufacturing, as no experimental evidence has been found of studies that directly address the problem of the FDM-printed part with geometric and dimensional tolerances and desirable surface quality for assembly.

scholarly journals Morphology and surface reconstructions of m-plane GaN

2002 ◽  
Vol 743 ◽  
Author(s):  
C. D. Lee ◽  
R. M. Feenstra ◽  
J. E. Northrup ◽  
L. Lymperakis ◽  
J. Neugebauer
Keyword(s):  
Molecular Beam Epitaxy ◽  
Low Temperature ◽  
Surface Morphology ◽  
Buffer Layer ◽  
Molecular Beam ◽  
Structural Quality ◽  
Surface Reconstructions ◽  
Gan Buffer Layer

ABSTRACTM-plane GaN(1100) is grown by plasma assisted molecular beam epitaxy on ZnO(1100) substrates. A low-temperature GaN buffer layer is found to be necessary to obtain good structural quality of the films. Well oriented (1100) GaN films are obtained, with a slate like surface morphology. On the GaN(1100) surfaces, reconstructions with symmetry of c(2×2) and approximate “4×5” are found under N- and Ga-rich conditions, respectively. We propose a model for Ga-rich conditions with the “4×5” structure consisting of ≥ 2 monolayers of Ga terminating the GaN surface.

Improvement of the crystalline quality of the ZnO epitaxial layer on a low-temperature grown ZnO buffer layer

2004 ◽  
Vol 266 (4) ◽  
pp. 505-510 ◽  
Author(s):  
J.F. Yan ◽  
Y.M. Lu ◽  
Y.C. Liu ◽  
H.W. Liang ◽  
B.H. Li ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Epitaxial Layer ◽  
Crystalline Quality ◽  
Zno Buffer Layer

Dislocation Behaviour in GexSi1-x Epilayers on (001)Si

1989 ◽  
Vol 160 ◽  
Author(s):  
Eric P. Kvam ◽  
D.M. Maher ◽  
C.J. Humphreys
Keyword(s):  
Dislocation Density ◽  
Film Thickness ◽  
Critical Thickness ◽  
Three Dimensional ◽  
Critical Value ◽  
Misfit Dislocations ◽  
Island Growth ◽  
Edge Type ◽  
Dislocation Behaviour ◽  
Step Mechanism

AbstractWe have observed that the nature of misfit dislocations introduced near the critical thickness in GexSi1-x alloys on (001)Si changes markedly in the region 0.4 ≤ x ≤ 0.5. At or below the lower end of this compositional range, the observed microstructure is comprised almost entirely of 60° type dislocations, while at the high end, the dislocation structure is almost entirely Lomer edge type. Concurrent with this change, the dislocation density at the top of the epilayer varies by a factor of about 60X. Similarly, several other observables (e.g. dislocation length and spacing) also change appreciably.Part of the reason for the morphological variation seems to be a change in the source for dislocation introduction, in conjunction with a change in glide behaviour of dislocations as a function of film thickness. Evidence will be presented that indicates strain, as well as thickness, has a critical value for some dislocation introduction mechanisms, and that these together determine the resulting microstructure.Furthermore, it appears unlikely that the edge-type Lomer dislocations which appear at about x = 0.5 are either introduced directly, by climb, or grown in, as in the three-dimensional island growth and coalescence which occurs when x approaches unity. Instead, a two-step mechanism involving glissile dislocations is proposed and discussed.

Improvement in the Quality of ZnTe Epilayers Grown on GaAs Substrates by Introducing a Low-Temperature Buffer Layer

2009 ◽  
Vol 48 (8) ◽  
pp. 080208 ◽  
Author(s):  
Qixin Guo ◽  
Yusuke Sueyasu ◽  
Tooru Tanaka ◽  
Mitsuhiro Nishio ◽  
Juncheng Cao
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Gaas Substrates

The Initial Stages of MBE Growth of InSb on GaAs(100) - A High Misfit Heterointerface

1989 ◽  
Vol 159 ◽  
Author(s):  
C.J. Kiely ◽  
A. Rockett ◽  
J-I. Chyi ◽  
H. Morkoc
Keyword(s):  
Three Dimensional ◽  
Misfit Strain ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Island Growth ◽  
Mbe Growth ◽  
Edge Type ◽  
Transmission Electron ◽  
Interfacial Defects ◽  
Square Array

ABSTRACTThe initial stages of heteroepitaxy of InSb on GaAs(100) grown by MBE have been studied by transmission electron microscopy. Three dimensional InSb island growth occurs in which the majority of the 14.6% misfit strain is accommodated by a square array of a/2<011= edge-type misfit dislocations. The implications of each island having a well defined defect array before coalescence into a continuous epilayer are discussed. Some 600-type a/2<101= interfacial defects and associated threading dislocations are also observed in coalesced films and possible reasons for their existence are explained. A strong asymmetrical distribution of planar defects in the InSb islands is observed and the origin of the asymmetry is discussed. Finally some evidence for local intermixing in the vicinity of the interface is presented.

scholarly journals Effects of the Growth Time and the Thickness of the Buffer Layer on the Quality of the Carbon Nanotubes

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
J. Chuen
Keyword(s):  
Carbon Nanotubes ◽  
Buffer Layer ◽  
Silicon Substrate ◽  
Chemical Vapor ◽  
Growth Time ◽  
Material Basis ◽  
Good Material ◽  
Threshold Time ◽  
Direct Growth

Direct growth of carbon nanotubes (CNTs) array onto silicon substrate by the chemical vapor deposition (CVD) is reported. Experimental results show that the thickness of the buffer layer has a significant effect on the morphology and defects of the array, and when the buffer layer is about 15 nm, the best array on the silicon substrate can be obtained. Moreover, when the growth time is less than the threshold time (70 minutes), the array height will increase with the increase of the time. Importantly, when the growth time is higher than this threshold time, the growth of array will stop, but when the growth is continuing, the amorphous carbon and carbon can cluster, which will affect the structure of the array. These results provide a good material basis for the device, thermal, and conductivity technology.

Effects of the Nitridation Process of (0001) Sapphire on Crystalline Quality of InN Grown by RF-MBE

2004 ◽  
Vol 831 ◽  
Author(s):  
Daisuke Muto ◽  
Ryotaro Yoneda ◽  
Hiroyuki Naoi ◽  
Masahito Kurouchi ◽  
Tsutomu Araki ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Buffer Layers ◽  
Crystalline Quality ◽  
Constant Independent ◽  
Nitrogen Flux ◽  
Sapphire Substrates ◽  
Nitridation Process ◽  
Flux Modulation

ABSTRACTThe effects of the nitridation process of (0001) sapphire on crystalline quality of InN were clearly demonstrated. The InN films were grown on NFM (nitrogen flux modulation) HT-InN or LT-InN buffer layers, which had been deposited on nitridated sapphire substrates. We found that low-temperature nitridation of sapphire is effective in improving the tilt distribution of InN films. Whereas the twist distribution remained narrow and almost constant, independent of nitridation conditions, when LT-InN buffer layers were used. The XRC-FWHM value of 54 arcsec for (0002) InN, the lowest reported to date, was achieved by using the LT-InN buffer layer and sapphire nitridation at 300°C for 3 hours.

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